One of the most common objections from Muslims, Jews, and atheists is this: “The Old Testament presents God as uni-personal, not multi-personal.” The assumption is that only the New Testament introduces the idea of the Trinity. But if we examine Isaiah 48 carefully (especially within its literary and historical context) we find a profound challenge to that claim. In fact, Isaiah 48 contains one of the clearest Old Testament glimpses of God’s multi-personal reality.
Let’s begin in Isaiah 48:12:
"Hearken unto me, O Jacob and Israel, my called; I am he; I am the first, I also am the last."
Here, the speaker identifies Himself with an expression that in the Hebrew Bible belongs exclusively to YHWH: “I am He” (Hebrew: אֲנִי הוּא) and “I am the first and the last”. This is not a claim a prophet, angel, or king could legitimately make. In fact, “the first and the last” appears in other passages (Isaiah 41:4; 44:6) as a unique divine title of YHWH, later echoed in the New Testament in Revelation 1:17 — where Jesus applies it to Himself.
If there is any doubt about the identity of the speaker, verse 13 removes it:
"Mine hand also hath laid the foundation of the earth, and my right hand hath spanned the heavens: when I call unto them, they stand up together."
The speaker is explicitly the Creator of all things. Biblically, creation is the unique prerogative of YHWH alone (Isaiah 44:24). No creature, no matter how exalted, shares this work. This is pure monotheism, yet already we’re watching something unfold that will push us toward multi-personhood.
In verse 14, God continues:
"All ye, assemble yourselves, and hear; which among them hath declared these things? The LORD hath loved him: he will do his pleasure on Babylon, and his arm shall be on the Chaldeans."
Now we see a shift: YHWH speaks about another figure, “the one whom the LORD loves”, who will act against Babylon. This “arm” language is significant. In Isaiah, the “Arm of YHWH” often functions as a personal agent of God’s saving power (see Isaiah 53:1).
Verse 15 continues this theme:
"I, even I, have spoken; yea, I have called him: I have brought him, and he shall make his way prosperous."
The “I” here is still the same divine speaker from verses 12–13 , the eternal Creator. He calls, brings, and sends this figure. But now the scene reaches its theological climax in verse 16:
"Come ye near unto me, hear ye this; I have not spoken in secret from the beginning; from the time that it was, there am I: and now the Lord GOD, and his Spirit, hath sent me."
Let’s slow down here. The speaker, who has been YHWH from the beginning of the passage, says:
1. “From the time that it was, there am I” affirming His eternal presence and self-existence.
2. “And now the Lord GOD, and His Spirit, hath sent me.”
This is astonishing. The one speaking is YHWH (as proven in verses 12–13), yet He says He has been sent by “the Lord GOD” and “His Spirit.”
If we take the text at face value:
YHWH (the sender)
YHWH (the one sent — the speaker here)
The Spirit of YHWH (distinct from both)
Here in one verse, we see three distinguishable agents within the divine identity — the Sender (Lord GOD), the Sent (also YHWH), and the Spirit. This is not polytheism, because they share the same divine name, authority, and essence. But neither is it unipersonalism. It is exactly the pattern we find fully revealed in the New Testament as Father, Son, and Holy Spirit.
Why This Matters
This isn’t a Christian “reading back” into the Old Testament. Jewish exegetes themselves wrestled with passages like this. Some identified the “Spirit” here as a prophetic Spirit, others as a personal messenger of God. But the plain reading, that the Eternal YHWH is sent by YHWH alongside His Spirit, fits perfectly with the Trinitarian claim that God’s own Word and Spirit are fully divine and personally distinct.
So when someone claims the Old Testament only teaches a solitary, uni-personal deity, Isaiah 48:12–16 stands as a quiet but powerful contradiction. In the very Scriptures revered by Jews, Christians, and Muslims alike, we find a mysterious but unmistakable reality: YHWH sends YHWH, and the Spirit is with Him.